The invention pertains to archery bows, archery bow cam assemblies, and archery bow anchors.
Various types of archery bows have been developed, including traditional bows (i.e., long bows and recurved bows) and compound bows. All archery bows include a pair of opposed limbs extending from a handle of the bow. As an archer draws the bow by pulling on a drawstring, the limbs flex and store energy. This energy is transferred to the arrow as the archer releases the drawstring.
A compound bow is a popular design for archery bows and comprises incorporating one or more cams (for example, eccentric wheels or pulleys) into the bow. These bows use a cable system which extends over at least one cam rotatably mounted at a distal end of a bow limb to provide a mechanical advantage during the drawback of the drawstring. Such cams enable a peak draw force (i.e., a peak pull force on a drawstring of a bow to maintain a draw) to be reached in the middle of a draw such that the draw force drops at full draw.
With this arrangement, when the drawstring is in the full draw position, maximum potential energy is stored in the bow while the force required to maintain the drawstring in the full draw position is less than the maximum draw force of the bow. In short, as the drawstring is being drawn, the draw force applied to the bow increases to a maximum force and reduces to a lower draw force at the full draw position. Accordingly, maximum energy is stored in the limbs without requiring maximum force to be applied to the drawstring to hold the bow at the full draw position. This permits the archer to maintain aim on his target prior to release for a longer period of time for a better shot.
A general goal of archery bow designs is to increase the speed in which an arrow is projected by a bow. Arrows which fly faster can maintain a flatter trajectory over a greater distance than slower traveling arrows. This can enable faster flying arrows to be fired more accurately than slower traveling arrows.
Methods to increase arrow speed include maximizing energy transferred to the arrow from the bow. Accordingly, one general goal of archery bow design is to alleviate twisting of bow limbs that occurs during a draw. The twisting of bow limbs uses energy that cannot be transferred to the arrow, and therefore, the energy is lost for increasing arrow speed.
Another goal of archery bow designs is to decrease frictional forces between moving components within a bow, such as, for example, bearings and axles. The more frictional forces associated with moving components, the more energy not available for increasing arrow speed.
A general goal of compound bow designs is to provide a cable system that allows for fletching and sighting clearances. A fletching clearance is the area of clearance needed for the cross-sectional area of a bow shaft and radially extending feathers to pass unimpeded. A sighting clearance is a region for aiming at a target unimpeded by the cable system. The conventional method for establishing fletching and sighting clearances is to provide cable guards. However, the cable guards create unbalanced forces in the limbs which twist the limbs detrimentally as discussed previously.
In light of the above discussed goals, it would be desirable to develop an archery bow to minimize the above-mentioned design inefficiencies and difficulties.
In one aspect, the invention includes an archery bow having a first limb and a second limb, and a handle between the limbs. A rotating member comprises at least two cams rotatably joined to the first limb with a first of the at least two cams having an eccentric profile to provide a first camming surface and a second of the at least two cams having an eccentric profile to provide a second camming surface. The eccentric profile of the first cam is substantially symmetrical relative to the eccentric profile of the second cam. A string extends between the rotating member and second limb.
In another aspect, the invention includes an archery bow having a pair of flexible resilient bow limbs forming first and second outer bow limb ends and forming first and second inner bow limb ends. A handle connects the first and second inner bow limb ends and a string extends between the first and second outer bow limb ends. At least four cables extend between the first and second outer bow limb ends.
In yet another aspect, the invention includes an archery bow cam assembly having a first cam with an eccentric profile to provide a first camming surface. A second cam has an eccentric profile to provide a second camming surface and the eccentric profile of the first cam is substantially symmetrical relative to the eccentric profile of the second cam. The archery bow cam assembly includes a primary cam between the first and second cams.
In still another aspect, the invention includes an archery bow anchor having an outward surface with a plurality of peripheral discrete grooves. Each groove is laterally displaced from an adjacent groove.